1. Field of the Invention
The present invention relates to a position controller for an optical element.
2. Description of the Related Art
A type of image shake correcting mechanism (shake reduction mechanism/image stabilizing mechanism) which moves an optical element such as a lens element or an image sensor (image pickup device) in a plane orthogonal to an optical axis of an optical system (this optical element is hereinafter referred to as an image-shake-correcting optical element) to reduce image shake in an optical device such as a camera has been often used in recent years. The assignee of the present invention has proposed a structure for this type of image shake correcting mechanism wherein the moving range of the image-shake-correcting optical element is set to be greater than the effective moving range thereof for use in image shake correction (image shake reduction) to move the image-shake-correcting optical element to a position removed from an optical path, when an optical device that incorporates the image shake correcting mechanism moves from an operating state to a non-operating state. This structure is disclosed in Japanese Unexamined Patent Publication 2006-154674 (U.S. Pat. No. 7,630,618 B2).
Specifically, according to this proposed structure, there is provided a first movable frame movable in a specified direction in a plane orthogonal to an optical axis of an optical system, there is further provided a second movable frame which is supported by the first movable frame thereon to be movable in a direction different from the aforementioned specified direction in the plane orthogonal to the optical axis, and an image sensor (image pickup device) that serves as the image-shake-correcting optical element is fixed onto the second movable frame. The first movable frame and the second movable frame are moved to perform an image shake correcting operation, and the first movable frame is moved when the image sensor is moved to the aforementioned removed position.
According to this structure, the image-shake-correcting optical element (image sensor) which is removed (displaced) from an optical path and another optical element (e.g., a lens group or the like) which remains on the optical path can be positioned to lie in a plane orthogonal to the optical axis to thereby make it possible to achieve a reduction in length of the optical system in the optical axis direction when the optical device is in a non-operating state. In addition, as for the support structure for the image-shake-correcting optical element, a simplification of the structure can be achieved by making a single guide mechanism shared for two different purposes: for correcting image shake, and for removing (displacing) the image-shake-correcting optical element from an optical path.